Showing papers on "Base station published in 1988"

Propagation characteristics on microcellular urban mobile radio channels at 910 MHz

Abstract: To mitigate fading and reduce time dispersion on urban mobile radio channels, it has been proposed that future systems be configured with many small cells having low-powered base stations with street-lamp-level antennas. The results of measurements made to determine propagation characteristics on urban mobile radio channels with low-base-station antennas and line-of-sight between the base and mobile units are reported. Cumulative distribution functions for envelope fading as well as delay spread and frequency correlation statistics are presented. Comparisons are made with similar statistics for conventional channels. Results show that multipath propagation conditions would be significantly less severe if small-celled systems were implemented. Root mean square delay spread averages are reduced by a factor of approximately four in comparison with those typical in conventional systems. In addition, microcellular-type channels have Rician, rather than Rayleigh, envelope fading characteristics, and correspondingly different frequency correlation statistics, which offers further advantages. >

Radio broadcast communication systems with multiple loop antennas

Abstract: The invention comprises a low power broadcast system that is applicable especially to the so-called "electronic shelf" for retail stores, wherein the shelf edge carries price displaying modules that can be addressed and controlled from a central computer operated station. The system also permits the modules to broadcast back to the central station to confirm safe receipt of data and to give information as to stock levels, etc. A broadcast system avoids the need for wiring so that location changes are facilitated. To overcome the extremely noisy environment and to conserve power consumption, and hence battery life, the system employs a low frequency (132 kHz) reference carrier transmitted by the base station in discrete segmented packages, each of which frames a base data word transmitted by the base station and a corresponding module data word transmitted by the module a fixed period after the end of the base word; the base receiver than has precise time information for receipt of the module word and can "look" for it among the noise. The carrier received by the module is divided and the lower frequency used to demodulate the information-carrying transmission from the base station of the same frequency, avoiding the need for a phase locked loop detector; this lower frequency is also used for the module transmission. The module employs an air-cored loop antenna coil for the lower frequency and a ferrite-cored loop antenna for the higher reference frequency, while the store antenna is segmented for selection of the group of modules to be addressed; the antenna contacts the metal shelving to provide electromagnetic coupling thereto. Each module contains a microprocessor which controls the operation. Each module has "concealed" buttons which can be enabled and used to insert data to be transmitted therefrom. A charging circuit can be used as the power source employing the received RF carrier energy.

Wireless communication system with parallel polling

Abstract: A system which can provide short-range wireless data communication between a base station and a portable low-power module. Each portable module has an identification field by which it can be addressed separately. The identification field (which is 64 bits long in the presently preferred embodiment) can be parallel polled: By commanding all modules within range to respond, the base station can see the 64-bit identification fields combined in what is almost a "wired-OR" fashion. That is, if any one of the portable modules within range is pulsing (reporting a "1" bit) in a given time window, the base station will see a pulse; the base station will see the absence of a pulse only if all of the modules within range are reporting a "0" bit (not pulsing). This can be used, for example, to implement combinatorial logic functions on all (or some subfields of) the 64-bit identification field.

Portable wireless communication systems

Abstract: In portable wireless communication systems wherein subscriber stations communicate with a plurality of base stations each covering a predetermined area, communication lines are provided for dedicating to the exchange of the use status and observation result of radio channels with the plurality of base stations in order that each base station can autonomically manage the determination of a base station with which a subscriber station communicates, the selection of a radio channel to be used, and the like.

Outage probability calculations for multiple cochannel interferers in cellular mobile radio systems

Abstract: The calculation of outage probability is discussed in relation to cochannel interference problems inherent in mature cellular radio systems. Outage probability equations for coverage only and for single cochannel interferer situations are reviewed briefly, and examples of the application of these results to the estimation of the service area of a typical cellular base station are given. An analytical technique for multiple uncorrelated interferers in a Rayleigh fading environment is presented and the effect of several cochannel Rayleigh interferers on the service area of a cellular base station is examined.

Vehicle identification technique for vehicle monitoring system employing rf communications

Abstract: In a communication system having a communication channel for transmitting data between a base station (12) and a plurality of mobile radio units (14), wherein each radio unit has a unique identification (ID) code and wherein transmissions from each radio unit (14) to the base station (12) include the unit's ID code, a method is described for identifying which units are within RF communication proximity of the base station. The method includes: transmitting a range message (42, 110), including a low ID code parameter and a high ID code parameter, from the base station over the channel to elicit a response from at least one of the mobile radio units having an ID code between the low and high parameters; determining whether radio units transmitted a message in response to the range message (44, 112); and storing (116), responsive to transmission by the units, in an ID list (76) a signal representative of the respective ID code assigned to such transmitting units. These steps are repeated with different transmitted range messages until each of the radio units within RF proximity of the base station is appended to the ID list.

Radio broadcast communication systems

Abstract: The invention comprises a low power broadcast system that is applicable especially to the so-called "electronic shelf" for retail stores, wherein the shelf edge carries price displaying modules that can be addressed and controlled from a central computer operated station. The system also permits the modules to broadcast back to the central station to confirm safe receipt of data and to give information as to stock levels, etc. A broadcast system avoids the need for wiring so that location changes are facilitated. To overcome the extremely noisy environment and to conserve power consumption, and hence battery life, the system employs a low frequency (132 kHz) reference carrier transmitted by the base station in discrete segmented packages, each of which frames a base data word transmitted by the base station and a corresponding module data word transmitted by the module a fixed period after the end of the base word; the base receiver then has precise time information for receipt of the module word and can "look" for it among the noise. The carrier received by the module is divided and the lower frequency used to demodulate the information-carrying transmission from the base station of the same frequency, avoiding the need for a phase locked loop detector; this lower frequency is also used for the module transmission. The module employs an air-cored loop antenna coil for the lower frequency and a ferrite-cored loop antenna for the higher reference frequency, while the store antenna is segmented for selection of the group of modules to be addressed; the antenna contacts the metal shelving to provide electromagnetic coupling thereto. Each module contains a microprocessor which controls the operation. Each module has "concealed" buttons which can be enabled and used to insert data to be transmitted therefrom. A charging circuit can be used as the power source employing the received RF carrier energy.

Packet reservation multiple access for local wireless communications

Abstract: Packet reservation multiple-access (PRMA) allows a variety of information sources to share the same wireless access channel. Some of the sources, such as speech terminals, are classified as periodic and others, such as signaling are classified as random. Packets from all sources contend for access to channel time slots. When a periodic information terminal succeeds in gaining access, it reserves subsequent time slots for uncontested transmission. Computer simulations reveal that PRMA combines high bandwidth efficiency with low control complexity and the flexibility to accept information from a diversity of sources. It is considered a promising technique for wireless access to future telecommunications networks. >

Mobile communication position registering method and system therefor

Abstract: A mobile communication system including a plurality of radiotelephone base stations respectively covering a plurality of cells to define in combination a service area, a mobile unit capable of communicating with the radiotelephone base stations, and a radiotelephone control unit for connecting together each of the base stations and an ordinary telephone network, setting up and releasing a speech path between the each radiotelephone base station and the mobile unit, and adding a speech path for communication with another radiotelephone base station which is able to communicate with the mobile unit as it moves. The mobile unit is adapted to transmit and receive a plurality of channels at the same time so that it is capable of communicating with a plurality of radiotelephone base stations and registering its position to these base stations. The mobile unit successively registers its position to radiotelephone base stations with which it can communicate as it moves, so that the mobile unit can communicate with a telephone set in the telephone network without instantaneous disconnection via all the base stations where it has registered the position.

Mobile station equipment for a mobile radio telephone system

Abstract: A mobile station equipment for a mobile radio telephone system uses a voltage-controlled, temperature-compensated crystal oscillator (VC-TCXO) as a reference oscillator for local oscillators in frequency converters which convert an RF signal into IF signals. The oscillation frequency of the VC-TCXO is controlled by counting the second IF information and evaluating its difference from a certain reference value. At reception, the local oscillators have their reference frequency stabilized based on the stable frequency information from the base station. The equipment is compact and has reduced power dissipation and lower manufacturing cost.

Mobile radio telephone system

Abstract: In a mobile radio telephone system having multiple base stations controlled by a single line control unit, all base stations use a single common control channel in addition to their voice channels to communicate with a mobile station. If a calling signal from a mobile station is received by two or more base stations at once on the common control channel, the base station with the highest received signal level is selected. If voice signal quality becomes degraded during a call, the call is handed off to the base station with the highest received signal level.

PABX cordless telephone system

Abstract: A PABX cordless telephone system comprising a base station (10) and a plurality of handset (HS1 to HS5). The base station is connected to the public switching network and communicates with each handset by way of a respective duplex radio link. The operation of the PABX system is controlled by a micro-controller (16) in the base station. Micro-controllers are also present in each of the handsets. Security in the radio communication via the duplex radio links is provided by assigning an n-bit security address code, where n for example comprises 16 bits, to each handset. The signalling protocols in setting-up calls require the transmission of the full n-bit security code. In the interim periods the base station (10) carries out a security check on the handsets forming its system. Time, memory capacity in the micro-controllers and battery current can be saved while simultaneously achieving a high degree of security if the security check is carried out using m bits of the security codes where m

Mobile body position detection method

Abstract: PURPOSE: To detect the position of a mobile body with high accuracy more than in the unit of radio zone without requiring large installation investment by collating a reception electric field level in a mobile station of a base station transmission wave with the level in an electric field strength map so as to detect the position of the mobile station in existence in an area. CONSTITUTION: A mobile station 10 identifies and detects the reception electric field level of a base station transmission wave of a mobile body communication system for each of base stations 21-23, and the mobile station or a communication party to the mobile station 10 collates the level of an electric field strength map 90 whose position is made correspondent with the reception electric field level with the received electric field level to be detected for each of the base stations 21-23. Thus, the position of the mobile station 10 is detected more accurately than that in the radio unit zone of the mobile body communication system and the equipment required for the detention is simplified. COPYRIGHT: (C)1990,JPO&Japio

Method for approximately locating a mobile radio station

Abstract: 2.1 The invention is based on the object of keeping the technical expenditure for determining the approximate location of a mobile radio station low in a cellular radio telephone network. 2.2 To achieve the object, an individual base station number contained in a data message of the base station (15) is evaluated by the mobile radio station (20) and, if necessary, embedded into a voice signal to be sent out by the mobile radio station together with the subscriber number as location information. Voice signal and location information are transmitted via the base station and a line (L1) to a central evaluating station (30) which contains an evaluator (31) for the location information, that is to say the base station number and, if necessary, the subscriber number. The base station number specifies that the mobile radio station is located in the radio cell (10) of the relevant base station. 2.3 The invention is particularly suitable for the private mobile radio network C of the Federal German Post Office. 3. The drawing shows a diagrammatic representation of a cellular radio network.

Radio data protocol communications system and method

Abstract: A method and system of radio data communications especially useful in communicating over a special communications channel between a base station or cell site of a cellular telephone system and one of many user stations. Each user station communicates an alarm condition which may be either a burglar type alarm or an environmental alarm to the base station by responding on a compelled basis to a status request from the user station. The responses to such request are prevented from overlapping by fixed and unique time delays for each user station. This status response requires substantially a single bit width of data. If no response is received, this is also sensed. Secondly, a different category of request acquires from each selected user station several bits of data constituting an informational message, the request being sent to each user station in a cell in sequence, along with the particular unique time delay for each user station. Then the response are received in a group in sequence and are prevented from overlapping by use of these unique time delays.

Wireless optical communication system

Abstract: A wireless optical short-range communication system adapted for use as an intercom system. The system can be used in fast food restaurants and similar commercial institutions. The communication system (Fig. 4) includes a base station (12) to interconnect via optical communication a group of substantially similar physically spaced-apart, remote units (14, 16). Each one of the remote units includes an optical emitter (33, 37) to transmit an optical message-carrying beam to the base station, and an optical receptor (35, 39) to receive an optical message-carrying beam from the base station. The base station includes a receptor (30) for receiving the optical beam transmitted by the optical emitters of all of the remote units, and an optical emitter (28) to relay the received optical beam to the optical receptors of all the remote units. The base station includes a clock arrangement for synchronizing the operation of the system in a time division multiplexing carrier arrangement, by providing individual discrete time slots for the transmission of the signals from the remote units to the base unit, and for the transmission of the signals from the base unit to the remote units.

Investigation on a dynamic channel allocation for high capacity mobile radio systems

Abstract: The potential of a dynamic channel-allocation scheme is described, in particular, to increase the system capacity and to counteract the traffic bursts typically experienced in cellular mobile radio systems as a consequence of traffic jam, accidents, traffic lights, etc. In order to accomplish these improvements, an effective procedure, monitoring the link quality of all the active calls, is required. Practical considerations necessitate implementation such a control just at the base station. The affordability of this approach is considered, assuming as input parameters the correlation among wanted and interfering signals in both mobile-to-base and base-to-mobile directions. A software simulation of cellular systems with a broad range of applications has been used to evaluate the feasibility of such a channel assignment method. >

A method for locating a mobile station, as well as a mobile station and a base station for carrying out the method

Abstract: A method for locating a mobile station, and a mobile radio telephone station and a fixed base station for carrying out the method. Identity signals and a precise time pulse are transmitted from fixed radio telephone stations (S1-S5) of known locations. The transmission takes place either as a response to an interrogation transmitted from the mobile station or automatically at predetermined intervals. All of the fixed stations are in highly precise chronological synchronization, and the transmission time of a precise time pulse may be only a specific one, for example, occur­ ring at 1-second intervals. As this interval is great com­ pared with the travel time of the time pulse, it is possi­ ble, by eliminating any multiples of the fixed time inter­ val, on the basis of the arrival time of the time pulses received at the mobile station, to calculate at any given time the distance difference between two fixed stations and, with the aid of at least three fixed stations, the location of the mobile station. All that the method re­ quires is supplementation of an existing radio telephone network, and the signals concerning the localization can be transmitted, for example, on the auxiliary carrier waves of the system.

Digital time multiplexed mobile telephony system with an effective utilization of every time frame

Abstract: A digital time multiplexed mobile telephony system including a fixed base station and a plurality of mobile stations. For established connections the mobile stations are assigned channels, each corresponding to a time slot, from a plurality of time slots included in a time frame. The channels are assigned such that the mobile station to which the propagation time is shortest is assigned time slot 1, the mobile station to which the propagation time is next shortest being assigned the time slot 2, and so on. After the last time slot in the time frame there follows a guard time common to all time slots, for avoiding that the transmissions of the mobile stations wholly or partially overlap each other at the base station receiver.

Selection diversity in multiple interferer mobile radio systems

Abstract: Outage probability calculations are presented for the case when the transmission from a wanted base station is received by a mobile in the presence of multiple cochannel interfering signals. Ideal multiple branch selection diversity is employed to mitigate the effects of Rayleigh fading, which all the transmissions are assumed to suffer. The calculations are for an interference limited system where branch selection is made either on the basis of the best signal to interference ratio or, more practically, on the basis of strongest received power.

Method and equipment for synchronizing and transmitting information in a radio communication network

Abstract: The invention relates to a method and equipment for synchronizing and transmitting information in a radio communication network with fixed base stations (BS1, BS2) and movable mobile stations (MS1, MS2) as well as a plurality of radio channels, the base stations in said communication network being organized in a cellular system, and depending on the cellular system share in time multiplex a radio control channel such that each base station disposes over a frame with time slots within a super frame on the radio control channel. The base stations are synchronized by their receiving call and control signals transmitted on the radio control channel from other base stations during their frames, and time differences between internal time references in the base stations are determined with the aid of the received call and control signals. In accordance with the invention the transmission between the base stations and mobile stations takes place in time multiplex. Analogue information is digitalized before transmission. Information which is to be transmitted on a radio traffic channel is encoded before the transmission using an error-­correcting code extending over two or more successive time slots of a mobile station on the radio traffic channel.

Outage probability calculations for mobile radio systems with multiple interferers

Abstract: Outage probability calculations are presented for the case when the transmission from a wanted base station is received by a mobile in the presence of multiple cochannel interfering signals for the case where the transmissions suffer both log-normal shadowing and Rayleigh fading. The calculations consider the need to achieve simultaneously both a sufficient SNR and SIR to obtain satisfactory radio reception.

Portable wireless communication systems and method

Abstract: In portable wireless communication systems wherein subscriber stations (51, 52) communicate with a plurality of base stations (1-7) each covering a predetermined area (11-17), communication lines (40-49) are provided for dedicating to the exchange of the use status and observation result of radio channels with the plurality of base stations in order that each base station can autonomically manage the determination of a base station with which a subscriber station commu­nicates, the selection of a radio channel to be used, and the like.

Coded communication system with shared symbols

Abstract: A data communication system, including at least one base station and at least one portable module 120, wherein the portable module 120 transmits data on a high frequency, and the base station transmits data on a much lower frequency Transmissions by the base station use a pulse-width modulation scheme where the most commonly used signals correspond to the shortest pulse A "read" command is encoded as the same pulse width as one of the two write commands Since the direction of data transmission is known in overhead, there will be no ambiguity

Mobile communication system

Abstract: PURPOSE:To utilize an existing fixed circuit network to carry out the mobile communication by holding the using circuit when a mobile station moves to another service area during a busy mode and then calling again the held circuit after a radio circuit is set in a new service area. CONSTITUTION:When a mobile station 60-2 of an automobile, etc., dials a subscriber telephone set 30-1, etc., a radio circuit is set between the telephone 30-1 and a base station 60-1 of a radio zone 60. Then a call signal sent to the telephone 30-1 via an exchange 20. When a mobile station 60-2 moves close to a radio zone 50, the station 60-1 sends a radio zone switching alarm to the station 60-2 based on the monitor result for intensity of the transmitted radio wave and at the same time holds a telephone channel connected to the telephone 30-1 to inform a zone switching mode to the telephone 30-1. While the station 60-2 searches a radio channel to set up a radio circuit to a base station 50-1 of the zone 50 and sends the dial signals of the telephone 30-1 to the exchange 20 via the station 50-1, etc. Thus the exchange 20 cuts the held line and secures connection between the station 50-1 and the telephone 30-1. In such a way, an existing circuit network is utilized excepting for radio zones to improve the economical properties of the mobile communication.

Communication system with mobile stations

Abstract: A communication system including at least one mobile station. The system comprises a transmission line, a control station connected to the transmission line, the mobile station and a plurality of base stations connected to the transmission line. Each of the base stations includes a delaying device. Each of the base stations receives a first signal from the control station through the transmission line, transmits a second signal based on the first signal to the mobile station by radio, receives a third signal transmitted from the mobile station by radio, generates a fourth signal based on the third signal, delays the fourth signal by using the delaying device, and transmits the delayed fourth signal to the control station through the transmission line. The delaying device delays the fourth signal such that, when a plural number of the base stations simultaneously receive the third signal, the plural number of the base stations transmit the fourth signals with time delay to the control station through the transmission line.

Base station selecting system and portable terminal for mobile radio communication system

Abstract: PURPOSE: To suppress the deterioration of a frequency use efficiency due to the double use of the radio line at the time of using an on-vehicle repeater by selecting a micro zone base station and a small zone base station, which can be directly communicated, without using the on-vehicle repeater. CONSTITUTION: Micro zone base stations a101 and b102 and small zone base stations c201 and d202 transmit the base station information of present transmitting electric powers Pa, Pb, Pc and Pd. A portable terminal 20 periodically receives the signal from base stations a101, b102, c201 and d202. From the base station transmitting electric power code in a signal, the transmitting electric powers Pa, Pb, Pc and Pd and actually received receiving electric powers Ea, Eb, Ec and Ed are obtained, From the difference between both, propagation losses La, Lb, Lc and Ld of respective base stations are obtained. When the call is executed by the outgoing call and the incoming call, the portable terminal 20 selects the base station with the smallest of the propagation losses La, Lb, Lc and Ld of respective base stations and sends an communication request signal. COPYRIGHT: (C)1990,JPO&Japio

Network aspects of the GSM system (mobile communications)

Abstract: The network functions of the GSM (CEPT's Groupe Special Mobile) system are discussed. They can be divided into four broad categories: network functions required for basic service provision (call handling, subscriber authentication, emergency call, and supplementary services); network functions required for cellular operation (location registration and handover); additional network functions for call handling (queueing, off air call setup, security-related services); and operation and maintenance-oriented network functions. Several of these functions are unique for mobile networks, e.g., all the functions related to cellular operation. Most of the other functions require different or additional implementation in mobile networks as compared to fixed networks. >

On the hand-over rate in future cellular systems

Abstract: Consideration is given to the hand-over rate in future cellular radio communications systems in which a much higher number of subscribers and smaller cell sizes than in currently operating systems are to be expected. Three models are used to estimate future hand-over rates. The first is valid for simple roads, the second works with the area of a cell, and the third is a simulation in which information about the road net in the cell and the traffic behaviour of the vehicles is taken into account. The results obtained using all three models show that mobile subscribers will cross cell boundaries more often, so the number of hand-overs per second that a base station of the fixed network has to handle will be much higher than in current mobile telephone systems. >

Rapid processing of immediately successive arrival signals in a base station of a radio communication network

Abstract: In a base station (10) which is for use in a radio communication network comprising at least two telephone lines (111 to 11n) and a plurality of radio telephone sets (121 to 12m) and which comprises radio transceivers (131 to 13k) capable of selecting one of a control channel and a plurality of communication channels, a producing arrangement (16, 141 to 14n) is coupled between the radio telephone lines and the radio transceivers for producing, in response to a first arrival signal arriving at one of the telephone lines for producing a first call signal to make a first selected transceiver send the first call signal through a first selected channel towards the radio telephone sets. The first selected transceiver is selected from idle transceivers of the radio transceivers. The first selected channel is selected from the idle channels of the communication channels by a selecting arrangement (16 and 17). Responsive to a second arrival signal arriving at another of the telephone lines while the first call signal is sent through the first selected channel, the producing arrangement adds a channel code of a different one of the idle channels to make the first selected transceiver send the first call signal and the channel code of the different one of the idle channels.